I set out to create a Fusion Drive in my early 2008 20" aluminum iMac and was (apparently!) successful. I’ve only been using it for one day, but so far it is working very well. I’ve included a simple graph showing performance comparisons in seconds. In case anyone with a similar iMac wants to try this, I thought I'd describe what I did. I bought my early 2008 iMac new and have had very few problems with it. This is a fantastic model, in my opinion. Over the years I have upgraded the RAM from 2GB to 4GB (that’s the maximum) and the 320GB hard disk drive to 1TB. For being a 5-year-old computer, it runs extremely well, although it feels a little slow at times and the optical drive is starting to fail. Late last year Apple released new iMacs and Mac minis with an optional feature called Fusion Drive, which essentially fuses together a 128GB solid state drive (SSD) and a standard large hard disk drive (HDD) in such a way that the operating system sees just one disk drive. The cool thing is that the OS keeps track of what data you access most often and moves that data to the SSD automatically, dramatically speeding up disk access times on the computer. When I heard about this I wanted to try it myself and I found some very helpful resources online describing how to do it. Most required an external disk drive, but I didn’t want to rely on an external disk in order for my iMac to function, so I tried something else: I removed the faulty optical disk drive and replaced it with a 2.5” laptop HDD. I then replaced my old HDD with a new SSD. When I ran the commands required to combine the two new disks into a single “logical volume” I was able to reinstall OS X 10.8.2 and restore my data from a Time Machine backup. My computer now looks and feels just like it did before, right down to the position of the icons on my desktop, except it has no optical disk drive (I don’t care; I use an external one.) and it is really, really fast. Want specifics? This should point you in the right direction: Patrick Stein did some excellent testing to verify that Fusion Drive technology is possible on an older Mac here: http://jollyjinx.tumblr.com/post/34638496292/fusion-drive-on-older-macs-yes-since-apple-has He is careful in his later posts to warn people that he does not trust Apple’s default file system with his data and thus does not recommend creating a Fusion Drive on an important Mac. That said, I read his post, was convinced that it would work, and did what he recommended. You can find more straightforward directions here: http://www.macworld.com/article/2014011/how-to-make-your-own-fusion-drive.html iFixIt.com has the best step-by-step repair directions on the web. Their guide showing how to replace my iMac’s optical drive with a hard disk drive is superb: http://www.ifixit.com/Guide/Installing+iMac+Intel+20-Inch+EMC+2133+and+2210+Dual+Hard+Drive/8951/4 This is what I actually did: 1) Using Winclone 3.7 ($20 and totally worth the price!) I backed up my Boot Camp partition to a file on my hard disk drive. The Boot Camp partition was about 40GB and this took close to an hour. I have Windows XP installed on it. What can I say? I’m old school like that. 2) I backed up all of my data, including that Boot Camp partition backup file, to my Apple Time Capsule using Time Machine. I had about 724GB of data on my HDD. Using a USB or Firewire backup hard disk drive would also work fine. 3) I created a bootable Mountain Lion 10.8.2 USB flash drive using an 8GB flash drive I picked up from a local store for $12 US. These directions are very helpful for doing this: http://www.macworld.com/article/1167857/how_to_make_a_bootable_mountain_lion_install_drive.html 4) I ordered parts. I ordered a 2.5” fast HDD from NewEgg for $89. I used a Hitachi GST Travelstar 0S03563 1TB 7200 rpm with 32MB cache. I bought a cheap 128GB SSD on eBay for $76. The one I bought is a Samsung MZ7PA128HMCD-010H1. In order to get the SSD to work in place of my broken optical drive I had to buy an adapter. Luckily, I found exactly the one I needed at iFixIt.com for $60: http://www.ifixit.com/Apple-Parts/1...ems&utm_term=imac_intel_20"_emc_2133_and_2210 5) I disassembled my iMac very carefully and blew the dust out of it while I had it apart. I removed the old hard disk drive and set it aside. I plan to keep it around for a few weeks just in case the Fusion Drive setup fails and I need to go back to the old setup quickly. The SSD is the same size as a 2.5” laptop hard drive, but this iMac uses a standard 3.5” desktop hard drive, so I needed an adapter to make the SSD fit. Unfortunately the adapter I had on hand made the SSD sit about a half inch too far from the SATA data and power cables, and they couldn’t reach. I ended up using very strong Velcro to attach the SSD to the inside back wall of the iMac. It does not look pretty but it works well and is not going anywhere. I installed the 1TB HDD in place of my broken optical drive using the iFixIt guide mentioned above. Unfortunately the adapter I bought from them is about 2mm narrower than a real optical drive, so the screw holes do not line up. I had to drill out the black plastic bracket to make the screws reach. Again, not the prettiest job, but it worked just fine. I put it all back together. This took about an hour and a half but can be done in half that time if someone is already familiar with the inside of this iMac. 6) I booted it up using the Mountain Lion boot flash drive mentioned above. (Hold the Option key while booting to select the boot device you want.) Instead of installing the OS, I opened Terminal from the menu at the top of the screen and entered the commands described in the articles from Macworld and Patrick Stein. When this was complete, I rebooted, started up from the flash drive again, and proceeded to install OS X 10.8.2. At the end of the installation I chose to restore data from a Time Machine backup. Up to this point the whole process took about three hours. Restoring my 724GB of data took all night over a gigabit network cable. 7) When the restore was done I rebooted and my computer looked just like it did before I started, but was noticeably faster! I still had to restore my Boot Camp partition, which contained a working (and legal) copy of Windows XP. 8) I started Boot Camp Assistant and checked the box for “Install Windows 7”, even though this is not what I wanted to do. I set the partition size to 80GB (Use whatever size makes sense for your Windows installation.) and let it rip. The disk was partitioned automatically, but only after I inserted a valid Windows 7 DVD in my external optical disk drive. I don’t know how I would have gotten around this step if I had not had a Windows 7 disc and an optical drive lying around. Any suggestions? I’m curious to hear what others have tried. 9) When the partition was created, I exited Boot Camp Assistant and ejected the Windows 7 DVD. I used Winclone to restore my Boot Camp partition from the backup file I had created back in the first step. When this was done (about an hour later) my Windows XP partition was intact and worked just fine. The only problem I noticed with it is that shutting down causes Windows XP to blue-screen, and I haven’t spent any time trying to fix that. Since this only happens right at shutdown, I don’t care, so I probably won’t try to fix it. 10) That’s it! I am amazed at how well OS X runs like this. I did see iTunes crash once a few hours after doing this, and I have only been using the computer with my DIY Fusion Drive for about one full day, but otherwise it seems fine. If I end up with some horrible failure after a week or a month I’ll update this post! I hope this is useful to someone. This project took about four hours, not counting the time it takes to wait for long steps to complete on their own, and cost me about $257. The result is that my iMac runs significantly faster than it was designed to, and I plan to get at least another year or two of service out of it!